Thelazia species, commonly known as eye worms, are parasitic nematodes that cause thelaziasis, an infection that primarily affects the eyes and surrounding tissues. These parasites are transmitted by certain species of flies, which carry infective larvae and deposit them on the eyes of humans or animals while feeding on eye secretions. Thelazia callipaeda and Thelazia californiensis are the main species causing human thelaziasis, though the infection is more commonly found in animals like dogs and cattle.
Symptoms of thelaziasis include eye irritation, excessive tearing, itching, redness, and a sensation of a foreign body in the eye. In more severe cases, the infection can lead to conjunctivitis, corneal ulcers, or even impaired vision if left untreated. The worms are sometimes visible moving across the eye, which can be distressing for the affected individual.
Treatment for thelaziasis typically involves the manual removal of the worms from the eye using fine forceps, often performed by an eye specialist. In some cases, antiparasitic eye drops or oral medications may also be used to clear any remaining larvae. Preventive measures focus on reducing exposure to flies in endemic areas, which can be achieved by wearing protective eyewear and maintaining good hygiene to discourage flies from settling on the face.
